updates

Polynomial division modulo 5, gcd of two polynomials

I have to find the gcd $h$ of $f$ and $g$ in $\mathbb{F}_5[X]$. $f=X^9+X^8+X^7+X^6+X^5+X^4+X^3+X^2+X+1,$ $g=X^4+X-2.$ Here is my polynomial division: My s...

Published: Sep 06, 2026

general

Prove that an isometry preserves straight lines using intuitive geometry

This is an exercise of the book "Basic Mathematics" by Serge Lang, p.145. I've been working on this proof for a few days and I can't seem to mak...

Published: Sep 06, 2026

general

What makes the Cauchy principal value the "correct" value for a integral?

I haven't been able to find a good answer to this searching around online. There is a related old question here, but it never received much attention...

Published: Sep 06, 2026

news

Calculating expected value and variance of a probability density function

If I was given a probability density function: $$f(y) = \left\{\begin{array}{ll}\frac{3y^2(4-y)}{64} & \textrm{for } 0 \leq y \leq 4\\ 0 & \textrm...

Published: Sep 06, 2026

general

Prove Taylor expansion with mean value theorem

http://vapour-trail.blogspot.com/2006/03/brief-explanation-of-taylor-series-via.html provides an intuitive derivation of Taylor expansions from the mean v...

Published: Sep 06, 2026

updates

How to find the exact value of the cosine of 50 degree angle

I want to know the exact value of $\cos 50^\circ$. Actually I have already tried lot of times to solve but I cannot find the exact value of $\cos 50^\circ$.

Published: Sep 06, 2026

news

Calculating the coordinates of end terminal point of an arc from known r, arc in radyan and starting terminal point coordinates of the arc.

I have searched the site and found similar questions of mine but not exaclty I needed. I have an arc. I know the coordinates of the arc center (P0), r (ra...

Published: Sep 06, 2026

updates

More comprehensive General Topology's book than Engelking

Other than Engelking General Topology, I also come across other graduate general topology text such as Dugundji and Kelley, which I also find them interes...

Published: Sep 06, 2026

general

Solve for $X$ in matrix equation

How can I solve for $X$ in this matrix equation? $$\begin{bmatrix}-3&-8\\-9&5\end{bmatrix} X + \begin{bmatrix}4&-7\\3&-2\end{bmatrix} = \b...

Published: Sep 06, 2026

updates

Why is this answer wrong? (point of intersection between parabola and line)

Question: Use the discriminant to determine the number of points of intersection of the line $y=3x+5$ and the quadratic functions $f(x)=3x^2-2x-4$. Solve ...

Published: Sep 06, 2026